Combination therapy with fludarabine and rituximab followed by alemtuzumab in the first-line treatment of patients with chronic lymphocytic leukemia or small lymphocytic lymphoma: a phase 2 trial of the Minnie Pearl Cancer Research Network

Pentostatin, Cyclophosphamide, and Rituximab Followed by Alemtuzumab for Relapsed or Refractory Chronic Lymphocytic Leukemia: A Phase 2 Trial of the ECOG-Acrin Cancer Research Group (E2903)

Patients with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) may benefit from salvage chemoimmunotherapy (CIT). To explore further the use of CIT in the pre-novel agent era, ECOG-ACRIN undertook a phase 2 trial (E2903) for R/R CLL utilizing pentostatin, cyclophosphamide, and rituximab (PCR) followed by a consolidation course of alemtuzumab. This trial enrolled 102 patients with a median age of 64 years. Treatment consisted of 6 cycles of PCR followed by alemtuzumab for either 4 or 18 weeks depending on the initial response to PCR. The overall response after PCR (complete remission, CR, nodular partial remission, nPR, and partial remission, PR) was 55%. Major responses (CR or nPR) were achieved in 6%. The median overall survival (OS) and the median progression-free survival were 28 and 12 months, respectively. The most serious nonlethal adverse events were myelosuppression, febrile neutropenia, fatigue, nausea, and hyponatremia. PCR is an effective and well-tolerated nucleoside-based regimen for heavily pretreated CLL patients with R/R disease. The addition of alemtuzumab to CLL patients with a minor response (PR) or stable disease did not result in a significant number of higher responses (CR or nPR) nor an improvement in OS.

Canadian evidence-based guideline for the first-line treatment of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (cll) is the most common adult leukemia in North America. In Canada, no unified national guideline exists for the front-line treatment of cll; provincial guidelines vary and are largely based on funding. A group of clinical experts from across Canada developed a national evidence-based treatment guideline to provide health care professionals with clear guidance on the first-line management of cll. Consensus recommendations based on available evidence are presented for the first-line treatment of cll.

Alemtuzumab consolidation in chronic lymphocytic leukaemia: a phase I/II multicentre trial

OBJECTIVE

Despite high rates of long-lasting remissions in patients with chronic lymphocytic leukaemia (CLL) treated with chemoimmunotherapy, none of the current therapeutic approaches is curative with the exception of allogeneic transplantation. One strategy to extend progression-free survival and long-term survival might be the establishment of consolidation therapies.

METHODS

In this trial, patients with complete or partial second remission after fludarabine-based treatment received consolidation therapy with alemtuzumab. The aim of this phase I/II trial was to determine the maximal tolerable dose (MTD) of alemtuzumab consolidation and to evaluate safety and efficacy in patients who responded to second-line fludarabine-based treatment. Thirteen patients in complete (CR) or partial remission (PR) received alemtuzumab dose escalation starting with 10 mg intravenously (iv) once weekly for 8 wk and increasing in 10-mg intervals per dose level.

RESULTS

The main dose-limiting toxicities (DLTs) were infectious complications, and the MTD was determined at 10 mg. After alemtuzumab consolidation, seven of 13 patients (53%) were in CR, and four of these patients (30.7%) achieved minimal residual disease (MRD) negativity (<1 × 10E-4). At a median follow-up of 71.5 months, four patients were progression-free, with a median progression-free survival (PFS) of 28.5 months after the end of second-line treatment.

CONCLUSION

The results provide a safe and efficient schedule with weekly intravenous application of 10 mg of alemtuzumab as a consolidation regime in patients with CLL.

Residual cancer lymphocytes in patients with chronic lymphocytic leukemia after therapy show increased expression of surface antigen CD52 detected using quantitative fluorescence cytometry

BACKGROUND

Rituximab and alemtuzumab, mAbs used in recent years to treat CLL, are directed against antigens CD20 and CD52. CD20 is not highly expressed by CLL tumor cells, and rituximab does not have significant effectiveness in CLL unless combined with chemotherapy. Alemtuzumab targets CD52, which is much more highly expressed, and is currently the most effective agent used alone for CLL. Variability in expression of both antigens among these patients might be related to different individual therapeutic responses to mAb therapy.

PATIENTS AND METHODS

A total 95 patients diagnosed with CLL and/or SLL were divided into 4 groups: (1) untreated; (2) in complete or partial remission; (3) disease in progression; and (4) diagnosed with SLL. Flow cytometry of peripheral blood cells included gating of the CD5(+)CD19(+) tumor population, within which mean fluorescence intensity of fluorescein isothiocyanate (FITC) conjugated with anti-CD20 or anti-CD52 antibody was measured. The resulting expression of the 2 antigens was deduced from the calibration curve using Quantum FITC particles.

RESULTS

Expression of CD20 showed no significant differences among the 4 groups of patients. However, significantly greater expression of surface antigen CD52 was recorded in patient group 2 in complete or partial remission (P < .001).

CONCLUSION

The residual population of CLL cells after therapy is characterized by increased surface detection of CD52. Although the exact cause of this phenomenon is unknown, our results provide a basis to consider the potential for CLL consolidation therapy using alemtuzumab.

The prognostic impact of minimal residual disease in patients with chronic lymphocytic leukemia requiring first-line therapy

A proportion of patients with chronic lymphocytic leukemia achieve a minimal residual disease negative status after therapy. We retrospectively evaluated the impact of minimal residual disease on the outcome of 255 consecutive patients receiving any front-line therapy in the context of a detailed prognostic evaluation, including assessment of IGHV, TP53, NOTCH1 and SF3B1 mutations. The median follow-up was 73 months (range, 2-202) from disease evaluation. The median treatment-free survival durations for patients achieving a complete response without or with minimal residual disease, a partial response and no response were 76, 40, 11 and 11 months, respectively (P<0.001). Multivariate analysis revealed that three variables had a significant impact on treatment-free survival: minimal residual disease (P<0.001), IGHV status (P<0.001) and β2-microglobulin levels (P=0.012). With regards to overall survival, factors predictive of an unfavorable outcome were minimal residual disease positivity (P=0.014), together with advanced age (P<0.001), unmutated IGHV status (P=0.001), TP53 mutations (P<0.001) and elevated levels of β2-microglobulin (P=0.003). In conclusion, for patients requiring front-line therapy, achievement of minimal residual disease negativity is associated with significantly prolonged treatment-free and overall survival irrespective of other prognostic markers or treatment administered.

Rituximab maintenance after first-line therapy with rituximab, fludarabine, cyclophosphamide, and mitoxantrone (R-FCM) for chronic lymphocytic leukemia

The effectiveness of rituximab maintenance therapy in the treatment of chronic lymphocytic leukemia has been investigated in a phase 2 clinical trial that included an initial treatment with rituximab 500 mg/m2 on day 1 (375 mg/m2 the first cycle), fludarabine 25 mg/m2 on days 1 to 3, cyclophosphamide 200 mg/m2 on days 1 to 3, and mitoxantrone 6 mg/m2 on day 1 (R-FCM), for 6 cycles, followed by a maintenance phase with rituximab 375 mg/m2 every 3 months for 2 years. Sixty-seven patients having achieved complete response (CR) or partial response (PR) with R-FCM were given maintenance therapy. At the end of maintenance, 40.6% of patients were in CR with negative minimal residual disease (MRD), 40.6% were in CR MRD-positive, 4.8% remained in PR, and 14% were considered failures. Six of 29 patients (21%) who were in CR MRD-positive or in PR after R-FCM improved their response upon rituximab maintenance. The 4-year progression-free survival (PFS) and overall survival rates were 74.8% and 93.7%, respectively. MRD status after R-FCM induction was the strongest predictor of PFS. Maintenance with rituximab after R-FCM improved the quality of the response, particularly in patients MRD-positive after initial treatment, and obtained a prolonged PFS. This trial was registered at www.clinicaltrialsregister.eu as identifier #2005-001569-33.

Alemtuzumab use in relapsed and refractory chronic lymphocytic leukemia: a history and discussion of future rational use

In this review, we outline the clinical experience with single-agent alemtuzumab as a treatment for relapsed and refractory chronic lymphocytic leukemia (CLL) in both prospective and retrospective trials and describe the multiagent use of the drug with the goal of updating clinicians on recent developments and possible future rational combinations. Alemtuzumab, an antibody targeting the lymphocyte-specific surface marker CD52, is an approved agent for the treatment of CLL. Despite its demonstrated efficacy, likely secondary to concerns regarding infectious complications, it is most commonly used in the relapsed and refractory setting. Given alemtuzumab's unique mechanism of action it has been demonstrated to have activity in disease that is refractory to both alkylating agents and purine analogs. Furthermore, it has activity in TP53-mutated disease, which has the worst prognosis of any subset of CLL. Alemtuzumab has greater efficacy on circulating disease relative to nodal disease. Rational combinations are attempting to use these attributes to increase response rates in patients with relapsed and refractory disease.

Rituximab, ofatumumab and other monoclonal anti-CD20 antibodies for chronic lymphocytic leukaemia

BACKGROUND

Chronic lymphocytic leukaemia (CLL) accounts for 25% of all leukaemias and is the most common lymphoid malignancy in western countries. Standard treatments include mono- or polychemotherapies, usually combined with monoclonal antibodies such as rituximab or alemtuzumab. However, the impact of these agents remains unclear, as there are hints for increased risk of severe infections.

OBJECTIVES

The objectives of this review are to provide an evidence-based answer regarding the clinical benefits and harms of monoclonal anti-CD20 antibodies (such as rituximab, ofatumumab, GA101) compared to no further therapy or to other anti-leukaemic therapies in patients with CLL, irrespective of disease status.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 12, 2011), MEDLINE (from January 1990 to 4 January 2012), and EMBASE (from 1990 to 20 March 2009) as well as conference proceedings (American Society of Hematology, American Society of Clinical Oncology, European Hematology Association and European Society of Medical Oncology) for randomised controlled trials (RCTs).

SELECTION CRITERIA

We included RCTs examining monoclonal anti-CD20 antibodies compared to no further therapy or to anti-leukaemic therapy such as chemotherapy or monoclonal antibodies in patients with newly diagnosed or relapsed CLL.

DATA COLLECTION AND ANALYSIS

We used hazard ratios (HR) as effect measures for overall survival (OS), progression-free survival (PFS) and time to next treatment, and risk ratios (RR) for response rates, treatment-related mortality (TRM) and adverse events (AEs). Two review authors independently extracted data and assessed quality of trials.

MAIN RESULTS

We screened a total of 1150 records. Seven RCTs involving 1763 patients were identified, but only five could be included in the two separate meta-analyses we performed. We judged the overall the quality of these trials as moderate to high. All trials were randomised and open-label studies. However, two trials were published as abstracts only, therefore we were unable to assess the potential risk of bias for these trials in detail.Three RCTs (N = 1421) assessed the efficacy of monoclonal anti-CD20 antibodies (i.e. rituximab) plus chemotherapy compared to chemotherapy alone. The meta-analyses showed a statistically significant OS (HR 0.78, 95% confidence interval (CI) 0.62 to 0.98, P = 0.03, the number needed to treat for an additional beneficial effect (NNTB) was 12) and PFS (HR 0.64, 95% CI 0.55 to 0.74, P < 0.00001) advantage for patients receiving rituximab. In the rituximab-arm occurred more AEs, World Health Organization (WHO) grade 3 or 4 (3 trials, N = 1398, RR 1.15, 95% CI 1.08 to 1.23, P < 0.0001; the number needed to harm for an additional harmful outcome (NNTH) was 9), but that did not lead to a statistically significant difference regarding TRM (3 trials, N = 1415, RR 1.19, 95% CI 0.70 to 2.01, P = 0.52).Two trials (N = 177) evaluated rituximab versus alemtuzumab. Neither study reported OS or PFS. There was no statistically significant difference between arms regarding complete response rate (CRR) (RR 1.21, 95% CI 0.94 to 1.58, P = 0.14) or TRM (RR 0.31, 95% CI 0.06 to 1.51, P = 0.15). However, the CLL2007FMP trial was stopped early owing to an increase in mortality in the alemtuzumab arm. More serious AEs occurred in this arm (43% with alemtuzumab versus 22% with rituximab; P = 0.006).Two trials assessed different dosages or time schedules of monoclonal anti-CD20 antibodies. One trial (N = 104) evaluated two different rituximab schedules (concurrent arm: fludarabine plus rituximab (Flu-R) plus rituximab consolidation versus sequential arm: fludarabine alone plus rituximab consolidation). The comparison of the concurrent versus sequential regimen of rituximab showed a statistically significant difference of the CRR with 33% in the concurrent-arm and 15% in the sequential-arm (P = 0.04), that did not lead to statistically significant differences regarding OS (HR 1.14, 95% CI 0.20 to 6.65, P = 0.30) or PFS (HR 0.96, 95% CI 0.43 to 2.15, P = 0.11). Furthermore results showed no differences in occurring AEs, except for neutropenia, which was more often observed in patients of the concurrent arm. The other trial (N = 61) investigated two different dosages (500 mg and 1000 mg) of ofatumumab in addition to FluC. The arm investigating ofatumumab did not assess OS and a median PFS had not been reached owing to the short median follow-up of eight months. It showed no statistically significant differences between arms regarding CRR (32% in the FCO500 arm versus 50% in the FCO1000 arm; P = 0.10) or AEs (anaemia, neutropenia, thrombocytopenia).

AUTHORS' CONCLUSIONS

This meta-analysis showed that patients receiving chemotherapy plus rituximab benefit in terms of OS as well as PFS compared to those with chemotherapy alone. Therefore, it supports the recommendation of rituximab in combination with FluC as an option for the first-line treatment as well as for the people with relapsed or refractory CLL. The available evidence regarding the other assessed comparisons was not sufficient to deduct final conclusions.

Therapeutic antibodies against cancer

Antibody-based therapeutics against cancer are highly successful and currently enjoy unprecedented recognition of their potential; 13 monoclonal antibodies (mAbs) have been approved for clinical use in the European Union and in the United States. Bevacizumab, rituximab, and trastuzumab had sales in 2010 of more than $5 billion each. Hundreds of mAbs, including bispecific mAbs and multispecific fusion proteins, mAbs conjugated with small-molecule drugs, and mAbs with optimized pharmacokinetics, are in clinical trials. However, deeper understanding of mechanisms is needed to overcome major problems including resistance to therapy, access to targets, complexity of biological systems, and individual variations.

Choosing first-line therapy for chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) exhibits a highly variable natural history, but the addition of genomic risk stratification to traditional clinical staging systems has begun to explain the heterogeneous clinical course. Overall response to treatment has significantly improved over the past three decades and for the first time, a survival benefit has been demonstrated with the use of monoclonal antibodies in combination with cytotoxic chemotherapy. Newer therapeutic strategies have abrogated the adverse prognosis associated with some higher risk features, but other genetic subgroups remain at high risk for rapid disease progression and early mortality. Patients at advanced age or with significant comorbidity constitute a large proportion of the CLL population and present unique clinical challenges. This article will discuss the evolution of contemporary therapeutic approaches to the initial treatment of CLL, and highlight the ways in which risk-adapted therapeutic strategies are improving clinical outcomes.

Alemtuzumab for patients with chronic lymphocytic leukaemia

BACKGROUND

Chronic lymphocytic leukaemia (CLL) accounts for 25% of all leukaemias and is the most common lymphoid malignancy in Western countries. Standard treatment  includes mono- or poly-chemotherapies. Nowadays, monoclonal antibodies are added, especially alemtuzumab and rituximab. However, the impact of these agents remains unclear, as there are hints of an increased risk of severe infections.

OBJECTIVES

To assess alemtuzumab compared with no further therapy, or with other anti-leukaemic therapy in patients with CLL.

SEARCH METHODS

We searched CENTRAL and MEDLINE (from January 1985 to November 2011), and EMBASE (from 1990 to 2009) as well as conference proceedings for randomised controlled trials (RCTs). Two review authors (KB, NS) independently screened search results.

SELECTION CRITERIA

We included RCTs comparing alemtuzumab with no further therapy or comparing alemtuzumab with anti-leukaemic therapy such as chemotherapy or monoclonal antibodies in patients with histologically-confirmed B-cell CLL. Both pretreated and chemotherapy-naive patients were included.

DATA COLLECTION AND ANALYSIS

We used hazard ratios (HR) as an effect measure for overall survival (OS) and progression-free survival (PFS) and risk ratios (RRs) for response rates, treatment-related mortality (TRM) and adverse events. Two review authors independently extracted data and assessed the quality of trials.

MAIN RESULTS

Our search strategies led to 1542 potentially relevant references. Of these, we included five RCTs involving 845 patients. Overall, we judged the quality of the five trials as moderate. All trials were reported as randomised and open-label studies. However, two trials were published as abstracts only, therefore, we were unable to assess the potential risk of bias for these trials in detail. Because of the small number of studies in each analysis (two), the quantification of heterogeneity was not reliable.Two trials (N = 356) assessed the efficacy of alemtuzumab compared with no further therapy. One trial (N = 335), reported a statistically significant OS advantage for all patients receiving alemtuzumab (HR 0.65 (95% confidence interval (CI) 0.45 to 0.94; P = 0.021). However, no improvement was seen for the subgroup of patients in Rai stage I or II (HR 1.07; 95% CI 0.62 to 1.84; P = 0.82). In both trials, the complete response rate (CRR) (RR 2.61; 95% CI 1.26 to 5.42; P = 0.01) and PFS (HR 0.58; 95% CI 0.44 to 0.76; P < 0.0001) were statistically significantly increased under therapy with alemtuzumab. The potential heterogeneity seen in the forest plot could be due to the different study designs: One trial evaluated alemtuzumab additional to fludarabine as relapse therapy; the other trial examined alemtuzumab compared with no further therapy for consolidation after first remission.There was no statistically significant difference for TRM between both arms (RR 0.57; 95% CI 0.17 to 1.90; P = 0.36). A statistically significant higher rate of CMV reactivation (RR 10.52; 95% CI 1.42 to 77.68; P = 0.02) and infections (RR 1.32; 95% CI 1.01 to 1.74; P = 0.04) occurred in patients receiving alemtuzumab. Seven severe infections (64%) in the alemtuzumab arm in the GCLLSG CLL4B study led to premature closure.Two trials (N = 177), evaluated alemtuzumab versus rituximab. Neither study reported OS or PFS. We could not detect a statistically significant difference for CRR (RR 0.85; 95% CI 0.67 to 1.08; P = 0.18) or TRM (RR 3.20; 95% CI 0.66 to 15.50; P = 0.15) between both arms. However, the CLL2007FMP trial was stopped early due to an increase in mortality in the alemtuzumab arm. More serious adverse events occurred in this arm (43% versus 22% (rituximab), P = 0.006).One trial (N = 297), assessed the efficacy of alemtuzumab compared with chemotherapy (chlorambucil). For this trial, no HR is reported for OS. Median survival has not yet been reached, 84% of patients were alive in each arm at the data cut-off or at the last follow-up date (24.6 months). The TRM between arms shows no statistical significant difference (0.6% versus 2.0%; P = 0.34). Alemtuzumab statistically significantly improves PFS (HR 0.58; 95% CI 0.43 to 0.77; P = 0.0001), time to next treatment (23.3 compared with 14.7 months; P = 0.0001), ORR (83.2% versus 55.4%; P < 0.0001), CRR (24.2% versus 2.0%; P < 0.0001), and minimal residual disease rate (7.4% versus 0%; P = 0.0008) compared with chlorambucil. Statistically, significantly more asymptomatic (51.7% versus 7.4%) and symptomatic cytomegalovirus (CMV) infections (15.4% versus 0%) occurred in the patients treated with alemtuzumab.

AUTHORS' CONCLUSIONS

In summary, the currently available evidence suggests an OS, CRR and PFS benefit for alemtuzumab compared with no further therapy, but an increased risk for infections in general, CMV infections and CMV reactivations. The role of alemtuzumab versus rituximab still remains unclear, further trials with longer follow-up and overall survival as primary endpoint are needed to evaluate the effects of both agents compared with each other. Alemtuzumab compared with chlorambucil seems to be favourable in terms of PFS, but a longer follow-up period and trials with overall survival as primary endpoint are needed to determine whether this effect will translate into a survival advantage.

Post-remission intervention with alemtuzumab or rituximab to eradicate minimal residual disease in chronic lymphocytic leukemia: where do we stand?

The introduction of purine nucleoside analogs, later in combination with alkylating moieties and anti-CD20 immunotherapy, has profoundly improved the response rate and response duration in patients with chronic lymphocytic leukemia (CLL). The quality of clinical response following treatment may be improved to a level where residual leukemic cells become undetectable. As patients with this type of response appear to have extended survival rates, minimal residual disease (MRD) eradication is considered a new objective in CLL treatment with the aim of improving progression-free survival (PFS) and potentially overall survival (OS). This review therefore aims to overview the prognostic value of MRD eradication in CLL, the role of post-remission intervention with "passive" immunotherapy (alemtuzumab or rituximab) so as to eliminate persistent MRD or prevent MRD relapse, the impact of these strategies on disease-free survival and their possible adverse consequences. The data indicate a potential for post-remission alemtuzumab or rituximab to prolong PFS in CLL, although more investigations and longer follow-up are required before MRD-guided strategies can be recommended outside of clinical trials.

Cancer immunotherapy

Cancer immunotherapy consists of approaches that modify the host immune system, and/or the utilization of components of the immune system, as cancer treatment. During the past 25 years, 17 immunologic products have received regulatory approval based on anticancer activity as single agents and/or in combination with chemotherapy. These include the nonspecific immune stimulants BCG and levamisole; the cytokines interferon-α and interleukin-2; the monoclonal antibodies rituximab, ofatumumab, alemtuzumab, trastuzumab, bevacizumab, cetuximab, and panitumumab; the radiolabeled antibodies Y-90 ibritumomab tiuxetan and I-131 tositumomab; the immunotoxins denileukin diftitox and gemtuzumab ozogamicin; nonmyeloablative allogeneic transplants with donor lymphocyte infusions; and the anti-prostate cancer cell-based therapy sipuleucel-T. All but two of these products are still regularly used to treat various B- and T-cell malignancies, and numerous solid tumors, including breast, lung, colorectal, prostate, melanoma, kidney, glioblastoma, bladder, and head and neck. Positive randomized trials have recently been reported for idiotype vaccines in lymphoma and a peptide vaccine in melanoma. The anti-CTLA-4 monoclonal antibody ipilumumab, which blocks regulatory T-cells, is expected to receive regulatory approval in the near future, based on a randomized trial in melanoma. As the fourth modality of cancer treatment, biotherapy/immunotherapy is an increasingly important component of the anticancer armamentarium.

What is the best frontline therapy for patients with CLL and 17p deletion?

Chronic lymphocytic leukemia (CLL) is a lymphoproliferative disease with significant variation in disease progression, response to therapy, and survival outcome. Deletions of 17p or mutations of TP53 have been identified as one of the poorest prognostic factors, being predictive of short time for disease progression, lack of response to therapy, short response duration, and short overall survival. The treatment of patients with CLL has improved significantly with the development of chemoimmunotherapy, but this benefit was not pronounced in patients with 17p deletion. We compare various treatment strategies used in these patients, including FCR-like chemoimmunotherapy, alemtuzumab, other antibody combinations, or novel targeted therapies with promising results. Allogeneic stem cell transplantation offers the possibility for long-term disease control in these patients and should be considered early in younger, transplant-eligible patients. The current state of therapy is far from optimal and resources should be applied to studying therapeutic options for patients who have CLL with loss of p53 function.

Standard of care and novel treatments for chronic lymphocytic leukemia

PURPOSE

The standard of care and novel treatments for chronic lymphocytic leukemia (CLL) are reviewed.

SUMMARY

Recent advances in the treatment of CLL have dramatically changed the therapeutic landscape for both patients and health care professionals. The majority of conventional first-line therapies are noncurative and are only used to treat disease that is symptomatic or progressive and include chlorambucil, monotherapy with purine analogues, and combination chemotherapy. Immunotherapeutic agents such as rituximab and alemtuzumab may be indicated in select patient populations. However, because clinical trials have found that overall survival does not depend on the initial therapy, selection of first-line therapy should be based on patient-specific factors and the patient's goals for therapy with respect to response, survival, and symptom palliation. Progression-free survival time and time to treatment are critical endpoints for CLL treatment. An increasingly important endpoint is minimal residual disease (MRD), as it is considered to be the major cause of relapse in CLL. Finally, comparison of toxicities between different therapies is critical in CLL, as it is in other disease states. Several new agents are currently being evaluated for use in CLL, including alvocidib, oblimersen, and lumiliximab.

CONCLUSION

Chemotherapy remains the mainstay of treatment for the majority of patients with CLL. The introduction of rituximab, alemtuzumab, and bendamustine has improved the current outlook for patients with CLL. As overall survival does not appear to depend on the initial therapy, treatment should be selected based on patient-specific factors and goals. Challenges in CLL include determining when to initiate therapy, eradicating MRD, and managing therapeutic resistance.

The clinical application of monoclonal antibodies in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) represents the most prevalent adult leukemia. Treatment with chemotherapy over the past 3 decades has been palliative. The introduction of therapeutic antibodies has increased the number of treatment options for this disease. Despite this increase, our true understanding of the mechanism of action of antibody therapy in CLL remains limited. Rituximab, a CD20 antibody, is currently widely used in combination-based strategies for both previously untreated symptomatic CLL and as salvage therapy. Recent data suggest that the addition of rituximab to fludarabine with or without cyclophosphamide prolongs survival in younger patients with CLL. Other improved CD20 antibodies with promising clinical activity, including ofatumumab and GA-101, are coming forward. Alemtuzumab, a CD52 antibody, likewise has demonstrated benefit in both symptomatic, previously untreated CLL and in patients with relapsed disease but has less selectivity. Development of other therapeutic antibodies targeting alternative B-cell-specific antigens in CLL has been less successful, although many promising candidate antibodies and/or small modular immune pharmaceuticals (SMIPs) are coming forward. In addition, recent efforts to combine currently applied therapeutic antibodies with other biologic and targeted therapies with efficacy in CLL offers the potential to move toward alternative non-chemotherapy-based treatment approaches.

Chemoimmunotherapy of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) has long been regarded as an incurable disease of the elderly, worthy only of symptom palliation. Past generations of chemotherapy resulted in improved response rates, but did not change the natural history of the disease. Prolonged remissions and improvements in survival are, however, now possible owing to therapeutic advances including the use of purine analogs as frontline treatment and the emergence of monoclonal antibody-containing chemoimmunotherapy combinations. Moreover, consolidation strategies using non-cross resistant agents have improved the success rates of patients with residual disease at the end of induction treatment. Together, these new developments promise to deliver the tools necessary to render a state of minimal residual disease negativity in the majority of patients commencing treatment for CLL. This Review will outline the history and results of chemoimmunotherapy regimens that contain purine analogs and rituximab-the most successful combinations developed to date. We will also discuss how new developments in induction and consolidation strategies are leading the path towards cure.

Consolidation therapy with subcutaneous alemtuzumab after fludarabine and rituximab induction therapy for previously untreated chronic lymphocytic leukemia: final analysis of CALGB 10101

PURPOSE

To determine if alemtuzumab consolidation improves response rate and progression-free survival (PFS) after induction chemoimmunotherapy in previously untreated symptomatic patients with chronic lymphocytic leukemia.

PATIENTS AND METHODS

Patients (n = 102) received fludarabine 25 mg/m(2) intravenously days 1 to 5 and rituximab 50 mg/m(2) day 1, 325 mg/m(2) day 3, and 375 mg/m(2) day 5 of cycle 1 and then 375 mg/m(2) day 1 of cycles 2 to 6; fludarabine plus rituximab (FR) administration was repeated every 28 days for six cycles. Three months after completion of FR, patients with stable disease or better response received subcutaneous alemtuzumab 3 mg day 1, 10 mg day 3, and 30 mg day 5 and then 30 mg three times per week for 5 weeks.

RESULTS

Overall response (OR), complete response (CR), and partial response (PR) rates were 90%, 29%, and 61% after FR, respectively; 15% of patients were minimal residual disease (MRD) negative. Of 102 patients, 58 received alemtuzumab; 28 (61%) of 46 patients achieving PR after FR attained CR after alemtuzumab. By intent to treat (n = 102), OR and CR rates were 90% and 57% after alemtuzumab, respectively; 42% of patients became MRD negative. With median follow-up of 36 months, median PFS was 36 months, 2-year PFS was 72%, and 2-year OS was 86%. In patients achieving CR after FR, alemtuzumab was associated with five deaths resulting from infection (viral and Listeria meningitis and Legionella, cytomegalovirus, and Pneumocystis pneumonias), which occurred up to 7 months after last therapy. The study was amended to exclude CR patients from receiving alemtuzumab.

CONCLUSION

Alemtuzumab consolidation improved CR and MRD-negative rates after FR induction but caused serious infections in patients who had already achieved CR after induction and did not improve 2-year PFS or survival.

Use of alemtuzumab and rituximab consolidation in CLL: Pros and cons

As new therapeutic approaches have improved responses and outcomes in the treatment of chronic lymphocytic leukemia (CLL), the scientific community focuses now on diagnostic procedures and definitions of response in CLL. The use of monoclonal antibodies in particular has made it possible to treat CLL more effectively. The success of these new therapeutic tools can be traced back to the eradication of detectable disease in a significant number of patients. Therefore, the evaluation of minimal residual disease has become an important end point within clinical trials. This article describes various methods of assessing minimal residual disease and presents data demonstrating that new therapeutic approaches can eliminate residual malignant cells at the highest levels of sensitivity currently available. Although initial evidence suggests that the use of alemtuzumab induces a survival benefit when used in the consolidation setting, important safety issues remain to be resolved before this approach can be introduced in routine practice.

First-line treatment of chronic lymphocytic leukemia: role of alemtuzumab

The CD52-targeting antibody alemtuzumab is established in clinical practice with convincing activity in relapsed and refractory chronic lymphocytic leukemia (CLL), particularly in patients with high-risk features and adverse prognosis. In the CAM307 study alemtuzumab was tested and finally approved as a first-line single agent, even though the hurdle with chlorambucil as the contender was not set very high. Within clinical trials, the drug demonstrated an excellent ability to eliminate minimal residual disease in blood and bone marrow, which has been correlated with a corresponding survival advantage in patients. However, in the maintenance setting, infectious complications due to severe T cell suppression have been highlighted and do not allow clinicans to use alemtuzumab outside of clinical trials. This review discusses potential therapeutic niches and future applications of alemtuzumab with a focus on CLL front-line treatment.

Antibodies targeting cancer stem cells: a new paradigm in immunotherapy?

Antibody targeting of cancer is showing clinical and commercial success after much intense research and development over the last 30 years. They still have the potential to delivery long-term cures but a shift in thinking towards a cancer stem cell (CSC) model for tumor development is certain to impact on how antibodies are selected and developed, the targets they bind to and the drugs used in combination with them. CSCs have been identified from many human tumors and share many of the characteristics of normal stem cells. The ability to renew, metabolically or physically protect themselves from xenobiotics and DNA damage and the range of locomotory-related receptors expressed could explain the observations of drug resistance and radiation insensitivity leading to metastasis and patient relapse.Targeting CSCs could be a strategy to improve the outcome of cancer therapy but this is not as simple as it seems. Targets such as CD133 and EpCAM/ESA could mark out CSCs from normal cells enabling specific intervention but indirect strategies such as interfering with the establishment of a supportive niche through anti-angiogenic or anti-stroma therapy could be more effective.This review will outline the recent discoveries for CSCs across the major tumor types highlighting the possible molecules for intervention. Examples of antibody-directed CSC therapies and the outlook for the future development of this emerging area will be given.

Chronic lymphocytic leukemia: long-lasting remission with combination of cyclophosphamide, somatostatin, bromocriptine, retinoids, melatonin, and ACTH

The usual, initial therapy of patients with chronic lymphocytic leukemia (CLL) involves alkylating agents, corticosteroids, purine analogs, and monoclonal antibodies. The combination of these agents may lead to high complete and overall response rates, but all patients inevitably relapse, and median progression-free survival varies between 16 and 48 months. Further, these treatments present the risk of myelosuppression and infection, so that some of the combination regimens require antibiotic, antiviral, and antimycotic prophylaxis during and after their administration. We treated 4 patients with previously untreated progressive stage I Rai CCL, with a combination of cyclophosphamide, somatostatin, bromocriptine, retinoids, melatonin, and ACTH. All the patients had partial remission after 2 months and continued treatment, which was gradually reduced if lymphocyte count fell below 4000/microL. No patients had disease recurrence, and progression-free survival has not yet been reached (125, 121, 73, and 21 months, respectively). Toxicity was absent, and patients underwent the treatment at home, while carrying out their normal activities.

Richter syndrome: molecular insights and clinical perspectives

Richter syndrome (RS) represents the clinico-pathologic transformation of chronic lymphocytic leukaemia (CLL) to an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). The clinical definition of RS is heterogeneous, and encompasses at least two biologically different conditions: (i) CLL transformation to a clonally related DLBCL, that accounts for the majority of cases; (ii) development of a DLBCL unrelated to the CLL clone. In clonally related RS, the pathogenetic link between the CLL and the DLBCL phases is substantiated by the acquisition of novel molecular lesions at the time of clinico-pathologic transformation. RS is not a rare event in the natural history of CLL, since the cumulative incidence of RS at 10 years exceeds 10%. Prompt recognition of RS is known to be clinically useful, and may be favoured by close monitoring of CLL patients harbouring clinical and/or biological risk factors of RS development. Conventional risk factors that are independent predictors of RS development at the time of CLL diagnosis include: (i) expression of CD38; (ii) absence of del13q14 and (iii) lymph node size > or =3 cm. Other risk factors of RS development include CD38 genotype and usage of specific immunoglobulin variable genes. The molecular pathogenesis of RS has been elucidated to a certain extent. Acquisition of TP53 mutations and/or 17p13 deletion is a frequent molecular event in RS, as it is in other types of transformation from indolent to aggressive B-cell malignancies. Additional molecular alterations are being revealed by genome wide studies. Once that transformation has occurred, RS prognosis may be predicted by the RS score, based on performance status, LDH, platelet count, tumour size and number of prior therapies. Depending on patient's age and RS score, the therapeutic options for RS may range from conventional immunochemotherapy to allogeneic bone marrow transplantation.

Consolidation with alemtuzumab improves progression-free survival in patients with chronic lymphocytic leukaemia (CLL) in first remission: long-term follow-up of a randomized phase III trial of the German CLL Study Group (GCLLSG)

Alemtuzumab has shown considerable activity in untreated and relapsed chronic lymphocytic leukaemia. We report our long-term experience in 21 patients within a randomized phase III trial investigating the role of alemtuzumab for consolidation therapy after first-line fludarabine +/- cyclophosphamide, which was stopped prematurely due to severe infections. However, after a median follow-up of 48 months, progression-free survival was significantly prolonged for patients receiving alemtuzumab consolidation compared to those with no further treatment (P = 0.004). Minimal residual disease (MRD) levels were persistently reduced after consolidation. Therefore, despite toxicity, MRD reduction by alemtuzumab consolidation translates into a significantly improved long-term clinical outcome.